Footwear with improved sole assembly

ABSTRACT

An article of footwear, such as a sports shoe particularly for the practice of a racquet sport, the shoe including an outer sole assembly and an upper. A contact surface of the sole assembly has a first support portion including a first subdivision which borders a front end, from the lateral side to the medial side, as well as a second subdivision which extends from the first subdivision towards the rear end, and from the lateral side towards a medial side. The contact surface has a second support portion which extends from the first subdivision of the first portion towards the rear end, and from the second subdivision of the first portion towards the medial side. The average coefficient of friction of the first support portion is greater than the average coefficient of friction of the second support portion.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon French Patent Application No. 11/01292, filed Apr. 26, 2011, the disclosure of which is hereby incorporated by reference thereto in its entirety, and the priority of which is claimed under 35 U.S.C. § 119.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an article of footwear, such as a sports shoe, such sports shoe intended particularly for the practice of a racquet sport.

Footwear of this type can be used in fields such as tennis, badminton, squash, and the like.

2. Background Information

A shoe of the aforementioned type includes an outer sole assembly and a generally flexible upper, which is generally a low upper. The outer sole assembly is provided for contact with the ground.

Conventionally, the outer sole assembly extends lengthwise from a rear end to a front end, widthwise between a lateral side and a medial side, and height-wise between a surface for contacting the ground, adapted to be supported by the ground, and a connecting surface adapted to be connected to the upper.

Because the outer sole assembly is the portion of the shoe which cooperates with the ground, it is the center of a number of forces. In particular, the outer sole assembly transmits impulse forces exerted by the user, or wearer, or reaction forces coming from the ground. Therefore, the contact surface must be adapted to handle these forces. In particular, these forces can be intense and of a varying type depending upon the terrain and the sport practiced. The forces are generated by the movements of the user, which occur at highly variable speeds and accelerations and decelerations. These movements are generated when starting, braking, sliding, or taking or retaking support, or suddenly changing directions.

This is the case for example in the field of tennis, which requires constantly running over short distances in all directions. These small distances require the user to speed up and slow down repeatedly, at high frequency. Therefore, the contact surface is subject to a number of very intense forces. The contact surface is subject to abrasion forces due to friction, during acceleration, but also and especially during braking. Indeed, especially on clay the user slides the outer sole assembly on the ground, including when positioning himself or herself to hit a ball.

The prior art has taken into account the forces, and stresses, applied to the shoe and, more particularly, to the outer sole assembly.

This is particularly true in the field of tennis, in which the contact surface must be highly wear-resistant. Thus, the life span of the shoe is important, and the user can initiate hard acceleration and intense braking. This enables the user to move quickly and to position himself/herself accurately in the desired area in order to hit a ball.

Although the known tennis shoes generally meet the needs of the users, they are the source of several problems.

First, a number of users suffer injuries, resulting especially from the intense forces that are transmitted through the shoe.

Related to this, foot and leg discomfort is also notable, especially on hard terrain made of synthetic material, concrete, or tar. In contrast, a softer terrain is made of clay. Therefore, although suitable for terrain made of clay, conventional shoes are less suitable for terrain made of hard material.

Also notable is a deterioration of the shoe with respect to its overall structure: the upper sometimes separates locally from the outer sole assembly, particularly at the sides.

It has been further noted that the energy output of the user is not optimal. The user must exert much energy to adapt to the pace of play. Indeed, progress made in the field of racquets and balls has increased the speed of play. Therefore, the user must move faster, which is difficult to do with conventional footwear. Therefore, changes have been proposed.

For example, according to document FR 2 912 038-A1 and family member U.S. 2010/0170114-A1, the contact surface of a shoe sole assembly, that is to say the surface provided to take support on the ground, has two support portions. One of these support portions promotes adherence, on the medial side, and the other promotes sliding movements, on the lateral side. In fact, this aims at transversely modifying the adherence of the contact surface.

The shoe according to the aforementioned documents is essentially intended to solve the problems of wear and grip. Although this shoe has mitigated certain adverse effects observed with conventional shoes, it has not brought significant progress.

SUMMARY

In view of the preceding, the invention generally seeks to improve an article of footwear, such as shoe intended for the practice of a racquet sport or the like.

The footwear of the invention substantially reduces, or even eliminates, the occurrence of injuries in the area of the user's feet or legs.

Further, the footwear of the invention provides more comfort when used. In particular, with respect to tennis shoes, the invention seeks to achieve the same comfort on hard ground as that experienced on clay.

Still further, the footwear of the invention substantially limits, or even avoids, undesired deterioration of thereof. In particular, the invention seeks to prevent separation of the upper from the outer sole assembly.

And still further, the footwear of the invention enables the user to adapt to new equipment and in particular to increase his/her speed of play.

To this end, the invention provides an article footwear, more particularly an article of sports footwear, hereafter referred to as a “shoe,” for convenience in the description and not for limiting the invention, suitable for the practice of a racquet sport for example. The footwear, or shoe, includes an outer sole assembly and an upper, the outer sole assembly extending lengthwise from a rear end surface to a front end surface, widthwise between a lateral side surface and a medial side surface, and height-wise between a contact surface and a connection surface, the outer sole assembly having, from the rear end to the front end, a rear zone, a central zone, a metatarsal zone, and a front zone.

The contact surface of a shoe according to the invention includes a first support portion, the first support portion including a first subdivision which borders the front end, from the lateral side to the medial side in the front zone, and a second subdivision which extends from the first subdivision towards the rear end, and from the lateral side towards the medial side in the metatarsal zone. The contact surface having a second support portion which extends from the first subdivision of the first portion towards the rear end, and from the second subdivision of the first portion towards the medial surface in the metatarsal zone. The average coefficient of friction of the first support portion is greater than the average coefficient of friction of the second support portion.

The first support portion extends in the area of the toes, as well as in the area of the lateral portion of the metatarsus of the user. Much of the forces related to acceleration pass through this region of the foot. Indeed, the user tends to lift his/her heels in order to be able to react more quickly. Consequently, the second portion is effective when the foot is flat, in order to provide firm support during braking. In fact, the first and second portions are complementary to one another. The greater adherence of the first portion provides the outer sole assembly with the ability to transmit forces to accelerate. The reduced adherence, or even the slidability, of the second portion enables the sole assembly to slide when the shoe is flat on the ground. This scenario occurs when braking or sliding at the end of the displacements. Because the second support portion can slide, the user can anticipate the need to brake. This means that the user will brake earlier and perform a sliding movement, which is much longer than that which can occur with traditional shoes. The user is in a stable situation when sliding as a result of braking with the shoes of the invention. This is somewhat similar to a skier who advances while controlling his/her posture. Consequently, the user can hit a ball while braking. Contrary to what happens with prior art shoes, the user no longer needs to wait until stopping to strike the ball. As a result, the user can advantageously increase his/her speed of play.

With a shoe of this type, the user finds the same sensations and effects on hard terrain as on clay. The user is less subject to injuries.

A lengthy slide increases the braking time. Consequently, the stresses exerted on the foot or leg are weaker, because they dissipate over a longer period of time. A resulting advantage is a significant reduction, or even a disappearance, of injuries in the area of the user's feet or legs.

The invention makes the shoe more comfortable. Indeed, due to its ability to slide, a shoe according to the invention is capable of offering the same sensations on hard terrain as usually experienced on clay, and therefore the sensation of comfort associated with clay.

In addition, one advantage of the invention is the reduction, or even the disappearance, of ill-timed deterioration of the shoe. In particular, the upper remains affixed to the outer sole assembly because the stresses are reduced. A subsequent advantage is the lightness of the shoe. Indeed, it is no longer necessary to reinforce the shoe, and therefore to weigh it down, the shoe being capable of sustaining transverse stresses.

Finally, the invention generally improves shoes according to the prior art.

BRIEF DESCRIPTION OF DRAWINGS

Other features and advantages of the invention will be better understood from the following description, with reference to the annexed drawings showing, by way of non-limiting embodiments, how the invention can be embodied, and in which:

FIG. 1 is a front perspective view, on the side of the upper, of a shoe according to the first embodiment proposed for the invention;

FIG. 2 is a bottom view of the shoe of FIG. 1;

FIG. 3 is a cross section along the line of FIG. 2;

FIG. 4 is a cross section, similar to FIG. 3, of a second embodiment of the invention;

FIG. 5 is a cross section, similar to FIG. 3, of a third embodiment of the invention;

FIG. 6 is a cross section, similar to FIG. 3, of a fourth embodiment of the invention;

FIG. 7 is a cross section, similar to FIG. 3, of a fifth embodiment of the invention;

FIG. 8 is a cross section, similar to FIG. 3, of a sixth embodiment of the invention;

FIG. 9 is a view similar to FIG. 2, of a seventh embodiment of the invention;

FIG. 10 is a view similar to FIG. 2, of an eighth embodiment of the invention;

FIG. 11 is a view similar to FIG. 2, of a ninth embodiment of the invention;

FIG. 12 is a cross section along the line XII-XII of FIG. 11;

FIG. 13 is a view similar to FIG. 2, of a tenth embodiment of the invention;

FIG. 14 is a view similar to FIG. 2, of an eleventh embodiment of the invention; and

FIG. 15 is a view similar to FIG. 2, of a twelfth embodiment of the invention.

DETAILED DESCRIPTION

The embodiments described hereinafter relate more specifically to footwear intended for racquet sports, such as tennis. However, the invention can be applied to other disciplines, insofar as the same needs related to sliding are to be addressed.

The first embodiment is described below, with reference to FIGS. 1-3.

A tennis shoe is provided to receive the foot of the user, or user.

As known, the shoe includes an outer sole assembly 2 and an upper 3. The shoe 1 extends lengthwise, from a rear end or heel 4 to a front end or tip 5, and widthwise between a lateral side 6 and a medial side 7. Consequently, the outer sole assembly 2 extends lengthwise from the heel 4 to the tip 5, and widthwise between the lateral side 6 and medial side 7. The sole assembly 2 also extends height-wise, or depth-wise, between a contact surface 8 and a connection surface 9, possibly with a damping layer 46. The contact surface 8 is adapted to contact the ground. The connection surface 9 is used to affix the sole assembly 2 to the remainder of the shoe, for example by gluing.

As shown, the upper 3 includes a lower portion 10, provided to surround the foot, the shoe thereby having a low upper, which generally extends below the ankle, i.e., the upper having no high portion. However, the shoe could have a high upper, i.e., an upper that includes both the lower portion and an upper portion, the latter extending above the ankle. Alternatively, the shoe could have a mid-upper, i.e., an upper that extends to the ankle, or approximately to the ankle. Further, the shoe 1 is provided with a device 12 for reversibly tightening the upper 3. The device 12 is well-known to one of ordinary skill in the art and is not described in greater detail herein, except that the embodiment shown in FIG. 1 includes a pair of lace strands which extend along a path defined by lace guides situated on opposite sides of the upper in front of the opening that receives the user's foot, as well as a blocking mechanism which can block the laces in a tightened position when the shoe is worn.

To facilitate the description of the shoe, reference will be made of the outer sole assembly 2 having four successive zones. From the rear end 4 to the front end 5, the sole assembly 2 has a rear zone 21, adapted to extend in the area of the heel of the foot, a central zone 22, which extends in the area of the arch, a metatarsal zone 23, which extends in the area of the metatarsus of the user, and a front zone 24, which extends in the area of the toes.

According to the invention, as shown particularly in FIG. 2, the contact surface 8 has a first support portion 31, which includes first subdivision 32 which borders the front end 5 and extends from the lateral side 6 to the medial side 7 in the front zone 24, as well as a second subdivision 33 which extends from the first subdivision 32 towards the rear end 4, and from the lateral side 6 towards the medial side 7 in the metatarsal zone 23. The contact surface 8 has a second support portion 34 which extends from the first subdivision 32 of the first portion 31 towards the rear end 4, and from the second subdivision 33 of the first portion 31 towards the medial side 7 in the metatarsal zone 23. The average coefficient of friction of the first support portion 31 is greater than the average coefficient of friction of the second support portion 34.

The aforementioned arrangement enables the contact surface 8 to have a relatively high coefficient of friction in the area of the toes, as well as in the area of the lateral portion of the metatarsus. By comparison, the coefficient of friction of the contact surface 8 is substantially less in the area of the medial portion 34 of the metatarsus. This provides the outer sole assembly with the increased adherence needed to accelerate, as well as the ability to slide to brake. Indeed, for acceleration, the first support portion 31 is very effective, while, for braking, it is the second support portion 34 that is very effective.

According to the first embodiment, which is non-limiting, the second support portion 34 of the contact surface 8 extends from the second subdivision 33 of the first portion 31 to the medial side 7. Therefore, the medial portion of the metatarsus takes support on the ground, in the area in which the contact surface 8 has a reduced coefficient of friction. This enables the shoe to slide more easily on hard ground, when the foot is in flat support at the front. Each slide dissipates energy, which reduces the stresses in the legs of the user.

The first support portion 31 and second support portion 34 are provided to jointly cover the front zone 24 and metatarsal zone 23. These two zones extend in fact opposite the portion of the foot that deforms the most during displacements. It is this portion of the foot that manages most of the support forces. The arrangement of the two portions 31, 34 in the front 24 and metatarsal 23 zones, promotes a control of the acceleration and braking that are associated with the various movements on a tennis court, especially if the court is hard.

For example, the first subdivision 32 of the first support portion 31 is provided to extend in a direction from the front end 5 toward the rear end 4, along a distance between 10 and 25% of the length of the shoe. This enables the outer sole assembly 2 to properly adhere to the ground in the area of the toes.

Moreover, the second subdivision 33 of the first support portion 31 extends transversely along a distance between 10 and 35% of the width of the shoe. Therefore, with the second subdivision 33, the user finds the adherence to accelerate or to hit a smash, because under these conditions, the user shifts his/her front support forces to the lateral side, at least for one foot.

Good results can be achieved using rubber or materials having an equivalent coefficient of friction for the first support portion 31 which has greater adherence, and using materials such as polyurethane, polyamide, polyethylene, EVA, having lower coefficients of friction for the second support portion 34. The second portion 34 can also be provided with a rubber loaded with other materials adapted to reduce the grip of the portion, that is to say, to increase its ability to slide. For example, the rubber can be loaded with glass beads.

Good results can be achieved with coefficients of friction values for the constituent materials of the first portion 31 between 0.5 and 2.0, and coefficients of friction values for the constituent materials of the second portion 34 between 0.2 and 0.7. Although the ranges of values partially overlap, the choice of respective friction coefficients for the two portions 31, 34 is such that the ratio of the highest coefficient of friction divided by the lowest coefficient of friction is, although not limiting to the invention, between 2.5 and 10. For example, if the coefficient of friction of the second support portion 34 is 0.2, then the coefficient of friction of the first portion 31 is between 0.5 and 2.0. Alternatively, if the coefficient of friction of the second support portion 34 is 0.7, then the coefficient of friction of the first portion 31 is between 1.75 and 2.0. These values are given by way of examples, and other combinations are also within the scope of the invention.

The combinations of friction coefficients of the portions have an influence on the overall coefficient of the outer sole assembly of the shoe. The overall coefficient can for example be measured according to the EN 13287 standard, which, in its general principle, involves positioning a shoe on a flat reference surface made of ceramic or stainless steel, for example. The contact surface 8 of the outer sole assembly is therefore in contact with the reference surface in order to take the measurement. The aforementioned combinations of friction coefficients correspond in most cases to overall coefficient of friction values between 0.45 and 0.8.

FIG. 3 shows the first support portion 31 to be flush with the second support portion 34. These portions can be said to be co-extensive along the same plane or, with reference to the shoe, co-extensive along the bottom surface of the outer sole. This provides more surface smoothness to the contact surface 8, at least in the front 24 and metatarsal 23 zones. Consequently, the transition from a situation of adherence to a situation of sliding is progressive. This helps to reduce user fatigue.

With reference more particularly to FIG. 2, the contact surface 8 has a third support portion 41 which extends along the lateral side 6 in the rear zone 21, as well as a fourth support portion 42 which extends from the third portion 41 towards the medial side 7 in the rear zone 21. The average coefficient of friction of the third support portion 41 is greater than the coefficient of friction of the fourth portion of support 42. This makes it possible to manage the adherence and sliding of the sole assembly 2 in the area of the rear zone 21, that is to say, in the area of the heel of the foot. This arrangement completes the effects provided at the front. Once again, the grip in the rear zone 21 occurs on the lateral side, which stabilizes the heel when hitting a smash, for example.

Still according to the first embodiment, the fourth support portion 42 extends from the third support portion 41 to the medial side 7. It follows that these portions 42, 41 together cover the rear zone 21 of the sole assembly 2. It is therefore easier for the user to control the grip or sliding in the area of the heel.

By way of example, the third support portion 41 extends transversely along a distance between 10 and 45% of the width of the shoe. This distribution promotes sliding of the heel when braking on hard ground.

Still according to the first embodiment, the central zone 22 of the contact surface 8 of the sole assembly 2 is recessed, or concave. Consequently, only the rear zone 21, the metatarsal zone 23, and the front zone 24 take support on the ground. This arrangement markedly differentiates the front supports from the rear supports.

It has been noted that at least one of the support portions 31, 34, 41, 42 is in the form of a synthetic material layer.

Without being limiting, particularly in connection with FIG. 3, each support portion or layer 31, 34, 41, 42 extends strictly up to the area of the surface of the lateral side 6 or medial side 7 along which it runs. In other words, each of the support portions 31, 34, 41, 42 does not extend beyond an area of an edge of the lateral (6) side nor beyond an edge of the medial (7) side. As a result, the adherence or sliding of the sole assembly 2 is effective only in the area of the contact surface 8.

The other embodiments are described hereinafter with reference to FIGS. 4 to 15. For convenience, the elements shared with the first embodiment are designated by the same reference numerals, while the differences are highlighted.

A second embodiment is described with reference to FIG. 4, which has a transverse cross section similar to that of FIG. 3. In this figure, the second support portion 34 projects in relation to the first support portion 31, i.e., in a direction away from the upper. This embodiment amplifies the sliding during braking. The projection is between 0.1 and 3.0 mm, although good results can be obtained for values between 0.3 and 0.8 mm.

FIG. 5, illustrating a third embodiment, conversely provides for the first support portion 31 to project in relation to the second support portion 34. In this case, sliding is still significant, although attenuated in relation to the sliding obtained with the embodiments previously described.

With respect to a fourth embodiment, shown in FIG. 6, the second support portion 34 extends towards the upper 3 in the area of the medial side 7. This makes it possible to obtain a sliding effect on the medial side 7; this effect is sometimes useful when the user bends the leg.

Referring now to FIG. 7, illustrating a fifth embodiment, the first support portion 31 extends to the upper 3 in the area of the lateral side 6. This makes it possible to obtain a grip effect on the lateral side 6; this effect is useful, for example in hitting a smash, or initiating acceleration.

A sixth embodiment, according to FIG. 8, combines the sliding effects on the medial side 7 and the adherence effect on the lateral side 6. In this regard, the second support portion 34 extends towards the upper 3 in the area of the medial side 7, and the first support portion 31 extends towards the upper 3 in the area of the lateral side 6.

For the seventh embodiment, according to FIG. 9, the first support portion 31 extends over the entire periphery of the contact surface 8, and runs along the front end 5, the lateral side 6, the rear end 4, and the medial side 7 up to the plantar arch zone. Also, the second support portion 34 extends longitudinally in the central zone of the sole, in a region bounded by the first support portion 31. This structure is adapted to sliding movements carried out with the foot supported flat on the ground. Thus structured, the shoe is well suited to a more seasoned player. Here, the second support portion 34 extends in the four rear 21, central 22, metatarsal 23 and front 24 zones, and lengthwise in the rear zone 21 according to a value equal to or greater than 60% of the length of the rear zone 21. The first support portion 31 on the front medial zone makes it possible to quickly resume support and to start over at the end of the sliding movement. Without it being essential, an arrangement can be provided for which, as in the second embodiment, the second support portion 34 projects with respect to the first support portion 31.

For an eighth embodiment, according to FIG. 10, the first support portion 31 includes a third subdivision 38 which extends from the first subdivision 32 towards the rear end 4, and from the medial side 7 towards the lateral side 6. The shoe also includes a third support portion 41 which runs along the lateral side 6 and the rear end 4 in the rear zone 21, and the second support portion 34 extends longitudinally from the first support portion 31 up to the third support portion 41. This arrangement gives a little more importance to the sliding effect, compared to the embodiment according to FIG. 9.

Next, a ninth embodiment is shown in FIGS. 11 and 12. In this case, the outer sole assembly 2 includes a wear layer 45, which demarcates the contact surface 8, as well as a synthetic material layer 46, which extends from the connection surface 9 to the wear layer 45, crossing through the wear layer. The wear layer 45 is perforated in the second support portion 34. hi this regard, the wear layer has holes 47 that provide access to the synthetic material layer 46. Although not limiting to the invention, the wear layer 45 can be made of rubber or any equivalent material. The synthetic material layer can be made, for example, of ethyl vinyl acetate foam, or any equivalent material. For example, the synthetic material layer 46 can be provided to fill the holes 47 of the wear layer. This provides the contact surface 8 with surface homogeneity. The dots of material within the holes 47 define a zone having a lower coefficient of friction than the layer 45.

In addition, the contact surface 8 has a third support portion 41 which extends along the lateral side 6 in the rear zone 21. The contact surface 8 has a fourth support portion 42 which extends from the third portion 41 toward the medial side 7 in the rear zone 21; and in the fourth support portion 42, the wear layer 45 is perforated, providing the portion 41 with a lower coefficient of friction. The implementation technique at the rear of the boot is the same as for the front.

A tenth embodiment is shown using FIG. 13. Again, the first support portion 31 extends to the periphery of the contact surface 8, and runs along the front end 5, the lateral side 6, the rear end 4, and the medial side 7, and it has an indentation 31 a in the area of the big toe joint. The second support portion 34 extends longitudinally in the region bounded by the first support portion 31. What is specific to this embodiment is that the second support portion 34 extends lengthwise in the rear zone 21 according to a value equal to or less than 60% of the length of the rear zone 21. This reduces the ability of the heel to slide. Furthermore, the second support portion 34 has a transverse narrowing 51 in the area of the zone 31 a of the big toe joint, at the boundary of the metatarsal 23 and front 24 zones. This reduces the ability to slide in the area of the metatarsus and improves the ability to resume support at the end of the sliding period. The shoe according to this embodiment is suitable for a player having a very good level of play.

An eleventh embodiment is shown in FIG. 14. Again, the first support portion 31 extends to the periphery of the contact surface 8 and runs along the front end 5, the lateral side 6, the rear end 4, and the medial side 7. The second support portion 34 extends longitudinally in the region bounded by the first support portion 31. What is specific to this embodiment is that the second support portion 34 extends lengthwise in the rear zone 21 according to a value equal to or less than 15% of the length of the rear zone 21. This reduces the slidability of the heel a little further. The shoe according to this embodiment is suitable for an advanced player.

A twelfth embodiment is shown in FIG. 15. Again, the first support portion 31 extends to the periphery of the contact surface 8 and runs along the front end 5, the lateral side 6, the rear end 4, and the medial side 7. What is specific to this embodiment is that the second support portion 34 is divided. The second support portion 34 includes a front portion 55 housed in the front zone 24, and a setback portion 56 housed in the metatarsal zone 23. The front 55 and setback 56 portions are separated by a transverse bridge 57, which is a subdivision of the first support portion 31. The shoe according to this embodiment limits the ability to slide to the front half of the shoe, which is well-suited to high level players.

In any case, the invention is made from materials and using techniques of implementation known to one of ordinary skill in the art.

The invention is not limited to the embodiments described hereinabove, and includes all technical equivalents that fall within the scope of the claims that follow.

In particular, the shapes of the support portions may vary.

The constituent materials of the first 31 and second 34 support portions, respectively, are different.

In addition to the foregoing, the invention disclosed herein by way of exemplary embodiments suitably may be practiced in the absence of any element or structure which is not specifically disclosed herein. 

1. An article of footwear comprising: an upper; an outer sole assembly extending lengthwise from a rear end to a front end, widthwise between a lateral side and a medial side, and height-wise between a contact surface and a connection surface; the outer sole assembly comprising, between the rear end and the front end, the following successive zones: a rear zone; a central zone; a metatarsal zone; a front zone; the contact surface of the outer sole assembly comprising a first support portion and a second support portion; the first support portion of the contact surface comprising: in the front zone, a first subdivision bordering the front end from the lateral side to the medial side; in the metatarsal zone, a second subdivision extending from the first subdivision in a direction towards the rear end and extending from the lateral side in a direction towards the medial side; the second support portion extending as follows: from the first subdivision of the first portion in a direction toward the rear end; within the metatarsal zone, from the second subdivision of the first portion in a direction towards the medial side; an average coefficient of friction of the first support portion is greater than an average coefficient of friction of the second support portion.
 2. An article of footwear according to claim 1, wherein: the second support portion extends from the second subdivision of the first portion to the medial side.
 3. An article of footwear according to claim 1, wherein: the first support portion and the second support portion together cover the front zone and the metatarsal zone.
 4. An article of footwear according to claim 1, wherein: the first subdivision of the first support portion extends from the front end to the rear end, along a distance between 10 and 25% of the length of the shoe.
 5. An article of footwear according to claim 1, wherein: the second subdivision of the first support portion extends transversely along a distance between 10 and 35% the width of the shoe.
 6. An article of footwear according to claim 1, wherein: the first support portion is flush with the second support portion.
 7. An article of footwear according to claim 1, wherein: the contact surface comprises: a third support portion extending along the lateral side within the rear zone; a fourth support portion extending from the third portion towards the medial side within the rear zone; the average coefficient of friction of the third support portion is greater than the average coefficient of friction of the fourth support portion.
 8. An article of footwear according to claim 7, wherein: the fourth support portion extends from the third support portion to the medial side.
 9. An article of footwear according to claim 7, wherein: the third support portion extends transversely along a distance between 10 and 45% of the width of the shoe.
 10. An article of footwear according to claim 1, wherein: the contact surface is concave within the central zone.
 11. An article of footwear according to claim 1, wherein: at least one of the support portions comprises a synthetic material layer.
 12. An article of footwear according to claim 1, wherein: each of the support portion does not extend beyond an area of an edge of the lateral side nor beyond an edge of the medial side.
 13. An article of footwear according to claim 1, wherein: the second support portion projects in a direction away from the upper in relation to the first support portion.
 14. An article of footwear according to claim 1, wherein: the first support portion projects in a direction away from the upper in relation to the second support portion.
 15. An article of footwear according to claim 1, wherein: the second support portion extends to the upper in an area of the medial side.
 16. An article of footwear according to claim 1, wherein: the first support portion extends to the upper in an area of the lateral side.
 17. An article of footwear according to claim 15, wherein: the first support portion extends to the upper in an area of the lateral side.
 18. An article of footwear according to claim 1, wherein: the contact surface comprises an outer periphery; the first support portion extends to the outer periphery of the contact surface, along the front end, the lateral side, the rear end, and the medial side; the second support portion extends longitudinally in a region formed by the first support portion.
 19. An article of footwear according to claim 1, wherein: the first support portion further comprises a third subdivision extending from the first subdivision in a direction towards the rear end, and from the medial side in a direction towards the lateral side; the contact surface further comprises a third support portion extending along the lateral side and the rear end in the rear zone of the outer sole assembly; the second support portion extends longitudinally from the first support portion to the third support portion.
 20. An article of footwear according to claim 1, wherein: the outer sole assembly comprises: a wear layer demarcating the contact surface; and a synthetic material layer extending from the connection surface to the wear layer by crossing through the wear layer; the wear layer is perforated in the second support portion.
 21. An article of footwear according to claim 20, wherein: the contact surface further comprises: a third support portion extending along the lateral side in the rear zone; a fourth support portion extending from the third portion towards the medial side in the rear zone; the wear layer is perforated in the fourth support portion.
 22. An article of footwear according to claim 18, wherein: the second support portion extends lengthwise in the rear zone to an extent less than or equal to 60% of a length of the rear zone.
 23. An article of footwear according to claim 18, wherein: the support portion has a transverse narrowing at a boundary of the metatarsal and front zones.
 24. An article of footwear according to claim 18, wherein: the second support portion comprises two spaced-apart portions.
 25. An article of footwear according to claim 24, wherein: the two spaced-apart portions of the second support portion comprises a front portion housed in the front zone and a setback portion housed in the metatarsal zone. 